Generally, digital cameras are image-recording media capable of photographing a plurality of still images without using film. Such a digital camera typically uses an image pickup device, which is a kind of semiconductor device, such as a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS). In the digital camera, an object image formed on the image pickup device through a lens is converted into an electrical signal, e.g., by the image pickup device, and the electrical signal is stored as a digital signal in a mobile phone or personal digital assistant (PDA), in which the digital camera is mounted, or in a “stand-alone” digital still or video camera unit. In order to protect the image pickup device from contamination or pollution (i.e., from dust or water vapor), the image pickup device is generally sealed in a structural package.
Typical chip packages, however, only allow packaging of one single chip in each package. In the case where a digital camera module having multiple functions is necessary, a peripheral chip, such as a flash memory chip or a digital signal processor (DSP) chip, must be packaged in a single chip package in accordance with the conventional chip packaging method. Two such chip packages occupy more area in the mobile phone, PDA, or stand-alone camera unit, which accordingly is prone to adversely affect miniaturization thereof.
One way of solving the foresaid question is to fabricate more than one chip in a single package. FIG. 7 (related art) shows a typical stacked chip package 90, which includes two chips packaged in a single package structure. The package 90 includes a substrate 91, a first chip 93, a second chip 95, a cover 97 and a plurality of wires 98. The substrate 91 includes a board portion 910, a sidewall portion 912, and a receiving cavity 914 formed between the board portion 910 and the sidewall portion 912. Multiple conductive leads 915 are arranged on an upper surface of the board portion 910 and are exposed to the receiving cavity 914. The conductive leads 915 further extend to a bottom surface of the board portion 90, in order to electrically connect the package 90 to external circuitry. The first chip 93 is mounted on the upper surface of the board portion 910 and is received in the receiving cavity 914. The second chip 95 is directly mounted on the top of the first chip 93. Both of the first and second chips 93, 95 provide a plurality of conductive points on the upper surfaces thereof. Each wire 98 electrically connects a conductive point of the chips 93, 95 to a corresponding conductive lead 915 of the substrate 91. The cover 97 is fixed to the top of the sidewall 912 of the substrate 91 to enclose the receiving cavity 914.
However, the second chip 95 must be smaller in size than the first chip 93 to allow the conductive points of the first chip 93 to connect to the wires 98. As a result, the package 90 is unsuitable for an apparatus where an image sensor chip (the second chip), needs to be mounted on the top of a peripheral chip (the first chip) and has a size larger than the size of the peripheral chip.
In addition, the wires 98, which electrically connect the conductive points of the first chip 93 to the leads 915, may be damaged through contact with the second chip 95.
Therefore, an improved digital camera module using stacked chip package is desired in order to overcome the above-described shortcomings.